Continuity and adhesion of Au deposits on electronic substrates by utilizing nanoparticle suspensions

Since nanosized metals exhibit a considerably lower melting point compared to bulk materials, nanometallic particle coated films can be deposited and cured to obtain electric conductors at a relatively low processing temperature. In this study, suspensions with Au nanoparticles of average size 3.9 ± 0.7 nm were prepared and spin-coated onto several commonly used electronic substrates (Cu, Ni and Al), and then thermally processed in a protective atmosphere. Experimental results show that the degree of continuity of the coated film on the Cu substrate was better than that on the Ni substrate, which was in turn better than the Al substrate. It was also found that isothermally heating the suspension at 300 °C, a temperature greater than the melting point of the nanoparticles used, could produce fine Au deposits with acceptable adhesion. Worthy of notice is that, after a proper curing treatment, Au layers deposited with nanoparticle suspension exhibited superior adhesion to those produced by sputtering.